The remains of the Castle can be visited
Tudoburg Castle

The former hilltop castle Tudoburg stands at approximately 604 meters above sea level near Eigeltingen-Honstetten in the Konstanz district, Baden-Württemberg. Its history is marked by changing owners and an early decline, which turned it into a ruin even before the Thirty Years' War.
History+
The exact origins of the Tudoburg remain obscure, but it is believed that the Lords of Honstetten erected it between 1050 and 1150. Originally named Harperg or Hardberg, it was later renamed Tudoburg after Tuto von Wagenhausen. In 1362, the castle passed to the Lords of Hewen. When the Lordship of Hewen fell to Austria in 1398, the Tudoburg was included.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://de.wikipedia.org/wiki/Datei:Tudoburg_pallasreste.jpg
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 47.8800, 8.8875